calcaneus cal·ca·ne·us (kāl-kā'nē-əs) or cal·ca·ne·um (-nē-əm)n.pl.cal·ca·ne·i (-nē-ī') or cal·ca·ne·a (-nē-ə) The quadrangular bone at the back of the tarsus, the largest of the tarsal bones. Also called heel bone.